PROVIDER-SIGNATURE(7SSL) OpenSSL PROVIDER-SIGNATURE(7SSL)
NAME
provider-signature - The signature library <-> provider functions
SYNOPSIS
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
/*
* None of these are actual functions, but are displayed like this for
* the function signatures for functions that are offered as function
* pointers in OSSL_DISPATCH arrays.
*/
/* Context management */
void *OSSL_FUNC_signature_newctx(void *provctx, const char *propq);
void OSSL_FUNC_signature_freectx(void *ctx);
void *OSSL_FUNC_signature_dupctx(void *ctx);
/* Get the key types that a signature algorithm supports */
const char **OSSL_FUNC_signature_query_key_types(void);
/* Signing */
int OSSL_FUNC_signature_sign_init(void *ctx, void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_sign(void *ctx, unsigned char *sig, size_t *siglen,
size_t sigsize, const unsigned char *tbs, size_t tbslen);
int OSSL_FUNC_signature_sign_message_init(void *ctx, void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_sign_message_update(void *ctx, const unsigned char *in,
size_t inlen);
int OSSL_FUNC_signature_sign_message_final(void *ctx, unsigned char *sig,
size_t *siglen, size_t sigsize);
/* Verifying */
int OSSL_FUNC_signature_verify_init(void *ctx, void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_verify(void *ctx, const unsigned char *sig, size_t siglen,
const unsigned char *tbs, size_t tbslen);
int OSSL_FUNC_signature_verify_message_init(void *ctx, void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_verify_message_update(void *ctx, const unsigned char *in,
size_t inlen);
/*
* OSSL_FUNC_signature_verify_message_final requires that the signature to be
* verified is specified via a "signature" OSSL_PARAM, which is given with a
* previous call of OSSL_FUNC_signature_set_ctx_params().
*/
int OSSL_FUNC_signature_verify_message_final(void *ctx);
/* Verify Recover */
int OSSL_FUNC_signature_verify_recover_init(void *ctx, void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_verify_recover(void *ctx, unsigned char *rout,
size_t *routlen, size_t routsize,
const unsigned char *sig, size_t siglen);
/* Digest Sign */
int OSSL_FUNC_signature_digest_sign_init(void *ctx, const char *mdname,
void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_digest_sign_update(void *ctx, const unsigned char *data,
size_t datalen);
int OSSL_FUNC_signature_digest_sign_final(void *ctx, unsigned char *sig,
size_t *siglen, size_t sigsize);
int OSSL_FUNC_signature_digest_sign(void *ctx,
unsigned char *sig, size_t *siglen,
size_t sigsize, const unsigned char *tbs,
size_t tbslen);
/* Digest Verify */
int OSSL_FUNC_signature_digest_verify_init(void *ctx, const char *mdname,
void *provkey,
const OSSL_PARAM params[]);
int OSSL_FUNC_signature_digest_verify_update(void *ctx,
const unsigned char *data,
size_t datalen);
int OSSL_FUNC_signature_digest_verify_final(void *ctx, const unsigned char *sig,
size_t siglen);
int OSSL_FUNC_signature_digest_verify(void *ctx, const unsigned char *sig,
size_t siglen, const unsigned char *tbs,
size_t tbslen);
/* Signature parameters */
int OSSL_FUNC_signature_get_ctx_params(void *ctx, OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_signature_gettable_ctx_params(void *ctx,
void *provctx);
int OSSL_FUNC_signature_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
const OSSL_PARAM *OSSL_FUNC_signature_settable_ctx_params(void *ctx,
void *provctx);
/* MD parameters */
int OSSL_FUNC_signature_get_ctx_md_params(void *ctx, OSSL_PARAM params[]);
const OSSL_PARAM * OSSL_FUNC_signature_gettable_ctx_md_params(void *ctx);
int OSSL_FUNC_signature_set_ctx_md_params(void *ctx, const OSSL_PARAM params[]);
const OSSL_PARAM * OSSL_FUNC_signature_settable_ctx_md_params(void *ctx);
DESCRIPTION
This documentation is primarily aimed at provider authors. See
provider(7) for further information.
The signature (OSSL_OP_SIGNATURE) operation enables providers to
implement signature algorithms and make them available to applications
via the API functions EVP_PKEY_sign(3), EVP_PKEY_verify(3), and
EVP_PKEY_verify_recover(3) (as well as other related functions).
All "functions" mentioned here are passed as function pointers between
libcrypto and the provider in OSSL_DISPATCH(3) arrays via
OSSL_ALGORITHM(3) arrays that are returned by the provider's
provider_query_operation() function (see "Provider Functions" in
provider-base(7)).
All these "functions" have a corresponding function type definition
named OSSL_FUNC_{name}_fn, and a helper function to retrieve the
function pointer from an OSSL_DISPATCH(3) element named
OSSL_FUNC_{name}. For example, the "function"
OSSL_FUNC_signature_newctx() has these:
typedef void *(OSSL_FUNC_signature_newctx_fn)(void *provctx, const char *propq);
static ossl_inline OSSL_FUNC_signature_newctx_fn
OSSL_FUNC_signature_newctx(const OSSL_DISPATCH *opf);
OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as
macros in openssl-core_dispatch.h(7), as follows:
OSSL_FUNC_signature_newctx OSSL_FUNC_SIGNATURE_NEWCTX
OSSL_FUNC_signature_freectx OSSL_FUNC_SIGNATURE_FREECTX
OSSL_FUNC_signature_dupctx OSSL_FUNC_SIGNATURE_DUPCTX
OSSL_FUNC_signature_query_key_types OSSL_FUNC_SIGNATURE_QUERY_KEY_TYPES
OSSL_FUNC_signature_sign_init OSSL_FUNC_SIGNATURE_SIGN_INIT
OSSL_FUNC_signature_sign OSSL_FUNC_SIGNATURE_SIGN
OSSL_FUNC_signature_sign_message_init OSSL_FUNC_SIGNATURE_SIGN_MESSAGE_INIT
OSSL_FUNC_signature_sign_message_update OSSL_FUNC_SIGNATURE_SIGN_MESSAGE_UPDATE
OSSL_FUNC_signature_sign_message_final OSSL_FUNC_SIGNATURE_SIGN_MESSAGE_FINAL
OSSL_FUNC_signature_verify_init OSSL_FUNC_SIGNATURE_VERIFY_INIT
OSSL_FUNC_signature_verify OSSL_FUNC_SIGNATURE_VERIFY
OSSL_FUNC_signature_verify_message_init OSSL_FUNC_SIGNATURE_VERIFY_MESSAGE_INIT
OSSL_FUNC_signature_verify_message_update OSSL_FUNC_SIGNATURE_VERIFY_MESSAGE_UPDATE
OSSL_FUNC_signature_verify_message_final OSSL_FUNC_SIGNATURE_VERIFY_MESSAGE_FINAL
OSSL_FUNC_signature_verify_recover_init OSSL_FUNC_SIGNATURE_VERIFY_RECOVER_INIT
OSSL_FUNC_signature_verify_recover OSSL_FUNC_SIGNATURE_VERIFY_RECOVER
OSSL_FUNC_signature_digest_sign_init OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT
OSSL_FUNC_signature_digest_sign_update OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE
OSSL_FUNC_signature_digest_sign_final OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL
OSSL_FUNC_signature_digest_sign OSSL_FUNC_SIGNATURE_DIGEST_SIGN
OSSL_FUNC_signature_digest_verify_init OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT
OSSL_FUNC_signature_digest_verify_update OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE
OSSL_FUNC_signature_digest_verify_final OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL
OSSL_FUNC_signature_digest_verify OSSL_FUNC_SIGNATURE_DIGEST_VERIFY
OSSL_FUNC_signature_get_ctx_params OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS
OSSL_FUNC_signature_gettable_ctx_params OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS
OSSL_FUNC_signature_set_ctx_params OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS
OSSL_FUNC_signature_settable_ctx_params OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS
OSSL_FUNC_signature_get_ctx_md_params OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS
OSSL_FUNC_signature_gettable_ctx_md_params OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS
OSSL_FUNC_signature_set_ctx_md_params OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS
OSSL_FUNC_signature_settable_ctx_md_params OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS
A signature algorithm implementation may not implement all of these
functions. In order to be a consistent set of functions we must have at
least a set of context functions (OSSL_FUNC_signature_newctx and
OSSL_FUNC_signature_freectx) as well as a set of "signature" functions,
i.e. at least one of:
OSSL_FUNC_signature_sign_init and OSSL_FUNC_signature_sign
Used via EVP_PKEY_sign_init(3) and EVP_PKEY_sign(3). These
functions operate on pre-digested data (the "to be signed" or TBS
value).
OSSL_FUNC_signature_sign_message_init and OSSL_FUNC_signature_sign
Used via EVP_PKEY_sign_message_init(3) and EVP_PKEY_sign(3) when
signing a complete message. The implementation internally handles
message digesting.
OSSL_FUNC_signature_sign_message_init,
OSSL_FUNC_signature_sign_message_update and
OSSL_FUNC_signature_sign_message_final
Streaming variant of message signing, used via
EVP_PKEY_sign_message_init(3), EVP_PKEY_sign_message_update(3), and
EVP_PKEY_sign_message_final(3).
OSSL_FUNC_signature_verify_init and OSSL_FUNC_signature_verify
Used via EVP_PKEY_verify_init(3) and EVP_PKEY_verify(3). These
functions operate on pre-digested data.
OSSL_FUNC_signature_verify_message_init and OSSL_FUNC_signature_verify
Used via EVP_PKEY_verify_message_init(3) and EVP_PKEY_verify(3) when
verifying a complete message. The implementation internally handles
message digesting.
OSSL_FUNC_signature_verify_message_init,
OSSL_FUNC_signature_verify_message_update and
OSSL_FUNC_signature_verify_message_final
Streaming variant of message verification, used via
EVP_PKEY_verify_message_init(3), EVP_PKEY_verify_message_update(3),
and EVP_PKEY_verify_message_final(3).
OSSL_FUNC_signature_verify_recover_init and
OSSL_FUNC_signature_verify_recover
Used via EVP_PKEY_verify_recover_init(3) and
EVP_PKEY_verify_recover(3). Applicable only to signature schemes
that support signature recovery (such as RSA).
OSSL_FUNC_signature_digest_sign_init,
OSSL_FUNC_signature_digest_sign_update and
OSSL_FUNC_signature_digest_sign_final
Streaming digest-sign variant, used via EVP_DigestSignInit(3),
EVP_DigestSignUpdate(3), and EVP_DigestSignFinal(3).
OSSL_FUNC_signature_digest_verify_init,
OSSL_FUNC_signature_digest_verify_update and
OSSL_FUNC_signature_digest_verify_final
Streaming digest-verify variant, used via EVP_DigestVerifyInit(3),
EVP_DigestVerifyUpdate(3), and EVP_DigestVerifyFinal(3).
OSSL_FUNC_signature_digest_sign_init and OSSL_FUNC_signature_digest_sign
One-shot digest-sign variant, used via EVP_DigestSign(3).
OSSL_FUNC_signature_digest_verify_init and
OSSL_FUNC_signature_digest_verify
One-shot digest-verify variant, used via EVP_DigestVerify(3).
Important Note for TLS Support: For a provider signature implementation
to be usable within libssl for TLS connections, it must implement the
digest-sign and digest-verify functions
(OSSL_FUNC_signature_digest_sign_init/update/final or the one-shot
variant, and OSSL_FUNC_signature_digest_verify_init/update/final or the
one-shot variant). The TLS handshake code in libssl specifically
requires these digest functions and will not use implementations that
only provide the basic sign/verify functions
(OSSL_FUNC_signature_sign_init/sign or
OSSL_FUNC_signature_verify_init/verify).
The choice of which function set to implement depends on your use case:
• For general-purpose signature operations and TLS support: implement
the digest-sign and digest-verify functions.
• For operations on pre-digested data only: implement the basic sign
and verify functions.
• For signature schemes with recovery capability: additionally
implement the verify-recover functions.
The OSSL_FUNC_signature_set_ctx_params() and
OSSL_FUNC_signature_settable_ctx_params() functions are optional, but if
one of them is provided then the other one must also be provided. The
same applies to the OSSL_FUNC_signature_get_ctx_params() and
OSSL_FUNC_signature_gettable_ctx_params() functions, as well as the
"md_params" functions.
The OSSL_FUNC_signature_dupctx() function is optional. It is not yet
used by OpenSSL.
The OSSL_FUNC_signature_query_key_types() function is optional. When
present, it should return a NULL-terminated array of strings indicating
the key types supported by the provider for signature operations.
Otherwise the signature algorithm name must match the given key or match
the default signature algorithm name of the key, both checked using
EVP_SIGNATURE_is_a(3).
A signature algorithm must also implement some mechanism for generating,
loading or importing keys via the key management (OSSL_OP_KEYMGMT)
operation. See provider-keymgmt(7) for further details.
Context Management Functions
OSSL_FUNC_signature_newctx() should create and return a pointer to a
provider side structure for holding context information during a
signature operation. A pointer to this context will be passed back in a
number of the other signature operation function calls. The parameter
provctx is the provider context generated during provider initialisation
(see provider(7)). The propq parameter is a property query string that
may be (optionally) used by the provider during any "fetches" that it
may perform (if it performs any).
OSSL_FUNC_signature_freectx() is passed a pointer to the provider side
signature context in the ctx parameter. This function should free any
resources associated with that context.
OSSL_FUNC_signature_dupctx() should duplicate the provider side
signature context in the ctx parameter and return the duplicate copy.
Signing Functions
OSSL_FUNC_signature_sign_init() initialises a context for signing given
a provider side signature context in the ctx parameter, and a pointer to
a provider key object in the provkey parameter. The params, if not
NULL, should be set on the context in a manner similar to using
OSSL_FUNC_signature_set_ctx_params(). The key object should have been
previously generated, loaded or imported into the provider using the key
management (OSSL_OP_KEYMGMT) operation (see provider-keymgmt(7)).
OSSL_FUNC_signature_sign() performs the actual signing itself. A
previously initialised signature context is passed in the ctx parameter.
The data to be signed is pointed to be the tbs parameter which is tbslen
bytes long. Unless sig is NULL, the signature should be written to the
location pointed to by the sig parameter and it should not exceed
sigsize bytes in length. The length of the signature should be written
to *siglen. If sig is NULL then the maximum length of the signature
should be written to *siglen.
Message Signing Functions
These functions are suitable for providers that implement algorithms
that accumulate a full message and sign the result of that accumulation,
such as RSA-SHA256.
OSSL_FUNC_signature_sign_message_init() initialises a context for
signing a message given a provider side signature context in the ctx
parameter, and a pointer to a provider key object in the provkey
parameter. The params, if not NULL, should be set on the context in a
manner similar to using OSSL_FUNC_signature_set_ctx_params(). The key
object should have been previously generated, loaded or imported into
the provider using the key management (OSSL_OP_KEYMGMT) operation (see
provider-keymgmt(7)).
OSSL_FUNC_signature_sign_message_update() gathers the data pointed at by
in, which is inlen bytes long.
OSSL_FUNC_signature_sign_message_final() performs the actual signing on
the data that was gathered with
OSSL_FUNC_signature_sign_message_update().
OSSL_FUNC_signature_sign() can be used for one-shot signature calls. In
that case, tbs is expected to be the whole message to be signed, tbslen
bytes long.
For both OSSL_FUNC_signature_sign_message_final() and
OSSL_FUNC_signature_sign(), if sig is not NULL, the signature should be
written to the location pointed to by sig, and it should not exceed
sigsize bytes in length. The length of the signature should be written
to *siglen. If sig is NULL then the maximum length of the signature
should be written to *siglen.
Verify Functions
OSSL_FUNC_signature_verify_init() initialises a context for verifying a
signature given a provider side signature context in the ctx parameter,
and a pointer to a provider key object in the provkey parameter. The
params, if not NULL, should be set on the context in a manner similar to
using OSSL_FUNC_signature_set_ctx_params(). The key object should have
been previously generated, loaded or imported into the provider using
the key management (OSSL_OP_KEYMGMT) operation (see
provider-keymgmt(7)).
OSSL_FUNC_signature_verify() performs the actual verification itself. A
previously initialised signature context is passed in the ctx parameter.
The data that the signature covers is pointed to be the tbs parameter
which is tbslen bytes long. The signature is pointed to by the sig
parameter which is siglen bytes long.
Message Verify Functions
These functions are suitable for providers that implement algorithms
that accumulate a full message and verify a signature on the result of
that accumulation, such as RSA-SHA256.
OSSL_FUNC_signature_verify_message_init() initialises a context for
verifying a signature on a message given a provider side signature
context in the ctx parameter, and a pointer to a provider key object in
the provkey parameter. The params, if not NULL, should be set on the
context in a manner similar to using
OSSL_FUNC_signature_set_ctx_params(). The key object should have been
previously generated, loaded or imported into the provider using the key
management (OSSL_OP_KEYMGMT) operation (see provider-keymgmt(7)).
OSSL_FUNC_signature_verify_message_update() gathers the data pointed at
by in, which is inlen bytes long.
OSSL_FUNC_signature_verify_message_final() performs the actual
verification on the data that was gathered with
OSSL_FUNC_signature_verify_message_update(). The signature itself must
have been passed through the "signature"
(OSSL_SIGNATURE_PARAM_SIGNATURE) Signature parameter before this
function is called.
OSSL_FUNC_signature_verify() can be used for one-shot verification
calls. In that case, tbs is expected to be the whole message to be
verified on, tbslen bytes long.
Verify Recover Functions
OSSL_FUNC_signature_verify_recover_init() initialises a context for
recovering the signed data given a provider side signature context in
the ctx parameter, and a pointer to a provider key object in the provkey
parameter. The params, if not NULL, should be set on the context in a
manner similar to using OSSL_FUNC_signature_set_ctx_params(). The key
object should have been previously generated, loaded or imported into
the provider using the key management (OSSL_OP_KEYMGMT) operation (see
provider-keymgmt(7)).
OSSL_FUNC_signature_verify_recover() performs the actual verify recover
itself. A previously initialised signature context is passed in the ctx
parameter. The signature is pointed to by the sig parameter which is
siglen bytes long. Unless rout is NULL, the recovered data should be
written to the location pointed to by rout which should not exceed
routsize bytes in length. The length of the recovered data should be
written to *routlen. If rout is NULL then the maximum size of the
output buffer is written to the routlen parameter.
Digest Sign Functions
OSSL_FUNC_signature_digest_sign_init() initialises a context for signing
given a provider side signature context in the ctx parameter, and a
pointer to a provider key object in the provkey parameter. The params,
if not NULL, should be set on the context in a manner similar to using
OSSL_FUNC_signature_set_ctx_params() and
OSSL_FUNC_signature_set_ctx_md_params(). The key object should have
been previously generated, loaded or imported into the provider using
the key management (OSSL_OP_KEYMGMT) operation (see
provider-keymgmt(7)). The name of the digest to be used will be in the
mdname parameter.
OSSL_FUNC_signature_digest_sign_update() provides data to be signed in
the data parameter which should be of length datalen. A previously
initialised signature context is passed in the ctx parameter. This
function may be called multiple times to cumulatively add data to be
signed.
OSSL_FUNC_signature_digest_sign_final() finalises a signature operation
previously started through OSSL_FUNC_signature_digest_sign_init() and
OSSL_FUNC_signature_digest_sign_update() calls. Once finalised no more
data will be added through OSSL_FUNC_signature_digest_sign_update(). A
previously initialised signature context is passed in the ctx parameter.
Unless sig is NULL, the signature should be written to the location
pointed to by the sig parameter and it should not exceed sigsize bytes
in length. The length of the signature should be written to *siglen. If
sig is NULL then the maximum length of the signature should be written
to *siglen.
OSSL_FUNC_signature_digest_sign() implements a "one shot" digest sign
operation previously started through
OSSL_FUNC_signature_digest_sign_init(). A previously initialised
signature context is passed in the ctx parameter. The data to be signed
is in tbs which should be tbslen bytes long. Unless sig is NULL, the
signature should be written to the location pointed to by the sig
parameter and it should not exceed sigsize bytes in length. The length
of the signature should be written to *siglen. If sig is NULL then the
maximum length of the signature should be written to *siglen.
Digest Verify Functions
OSSL_FUNC_signature_digest_verify_init() initialises a context for
verifying given a provider side verification context in the ctx
parameter, and a pointer to a provider key object in the provkey
parameter. The params, if not NULL, should be set on the context in a
manner similar to OSSL_FUNC_signature_set_ctx_params() and
OSSL_FUNC_signature_set_ctx_md_params(). The key object should have
been previously generated, loaded or imported into the provider using
the key management (OSSL_OP_KEYMGMT) operation (see
provider-keymgmt(7)). The name of the digest to be used will be in the
mdname parameter.
OSSL_FUNC_signature_digest_verify_update() provides data to be verified
in the data parameter which should be of length datalen. A previously
initialised verification context is passed in the ctx parameter. This
function may be called multiple times to cumulatively add data to be
verified.
OSSL_FUNC_signature_digest_verify_final() finalises a verification
operation previously started through
OSSL_FUNC_signature_digest_verify_init() and
OSSL_FUNC_signature_digest_verify_update() calls. Once finalised no more
data will be added through OSSL_FUNC_signature_digest_verify_update(). A
previously initialised verification context is passed in the ctx
parameter. The signature to be verified is in sig which is siglen bytes
long.
OSSL_FUNC_signature_digest_verify() implements a "one shot" digest
verify operation previously started through
OSSL_FUNC_signature_digest_verify_init(). A previously initialised
verification context is passed in the ctx parameter. The data to be
verified is in tbs which should be tbslen bytes long. The signature to
be verified is in sig which is siglen bytes long.
Signature parameters
See OSSL_PARAM(3) for further details on the parameters structure used
by the OSSL_FUNC_signature_get_ctx_params() and
OSSL_FUNC_signature_set_ctx_params() functions.
OSSL_FUNC_signature_get_ctx_params() gets signature parameters
associated with the given provider side signature context ctx and stored
them in params. Passing NULL for params should return true.
OSSL_FUNC_signature_set_ctx_params() sets the signature parameters
associated with the given provider side signature context ctx to params.
Any parameter settings are additional to any that were previously set.
Passing NULL for params should return true.
Common parameters currently recognised by built-in signature algorithms
are as follows.
"digest" (OSSL_SIGNATURE_PARAM_DIGEST) <UTF8 string>
Get or sets the name of the digest algorithm used for the input to
the signature functions. It is required in order to calculate the
"algorithm-id".
"properties" (OSSL_SIGNATURE_PARAM_PROPERTIES) <UTF8 string>
Sets the name of the property query associated with the "digest"
algorithm. NULL is used if this optional value is not set.
Note that when implementing a signature algorithm that gathers a full
message, like RSA-SHA256, the "digest" and "properties" parameters
should not be used. For such implementations, it's acceptable to simply
ignore them if they happen to be passed in a call to
OSSL_FUNC_signature_set_ctx_params(). For such implementations,
however, it is not acceptable to have them in the OSSL_PARAM array
that's returned by OSSL_FUNC_signature_settable_ctx_params().
"signature" (OSSL_SIGNATURE_PARAM_SIGNATURE) <octet string>
Sets the signature to verify, specifically when
OSSL_FUNC_signature_verify_message_final() is used.
"digest-size" (OSSL_SIGNATURE_PARAM_DIGEST_SIZE) <unsigned integer>
Gets or sets the output size of the digest algorithm used for the
input to the signature functions. The length of the "digest-size"
parameter should not exceed that of a size_t.
"algorithm-id" (OSSL_SIGNATURE_PARAM_ALGORITHM_ID) <octet string>
Gets the DER-encoded AlgorithmIdentifier for the signature
operation. This typically corresponds to the combination of a
digest algorithm with a purely asymmetric signature algorithm, such
as SHA256WithECDSA.
The ASN1_item_sign_ctx(3) function relies on this operation and is
used by many other functions that sign ASN.1 structures such as
X.509 certificates, certificate requests, and CRLs, as well as OCSP,
CMP, and CMS messages.
"nonce-type" (OSSL_SIGNATURE_PARAM_NONCE_TYPE) <unsigned integer>
Set this to 1 to use deterministic digital signature generation with
ECDSA or DSA, as defined in RFC 6979 (see Section 3.2 "Generation of
k"). In this case, the "digest" parameter must be explicitly set
(otherwise, deterministic nonce generation will fail). Before using
deterministic digital signature generation, please read RFC 6979
Section 4 "Security Considerations". The default value for "nonce-
type" is 0 and results in a random value being used for the nonce k
as defined in FIPS 186-4 Section 6.3 "Secret Number Generation".
The FIPS provider does not support deterministic digital signature
generation.
"kat" (OSSL_SIGNATURE_PARAM_KAT) <unsigned integer>
Sets a flag to modify the sign operation to return an error if the
initial calculated signature is invalid. In the normal mode of
operation - new random values are chosen until the signature
operation succeeds. By default it retries until a signature is
calculated. Setting the value to 0 causes the sign operation to
retry, otherwise the sign operation is only tried once and returns
whether or not it was successful. Known answer tests can be
performed if the random generator is overridden to supply known
values that either pass or fail.
The following parameters are used by the OpenSSL FIPS provider:
"fips-indicator" (OSSL_SIGNATURE_PARAM_FIPS_APPROVED_INDICATOR)
<integer>
A getter that returns 1 if the operation is FIPS approved, or 0
otherwise. This may be used after calling either the sign or verify
final functions. It may return 0 if either the "digest-check", "key-
check", or "sign-check" are set to 0.
"verify-message" (OSSL_SIGNATURE_PARAM_FIPS_VERIFY_MESSAGE <integer>
A getter that returns 1 if a signature verification operation acted
on a raw message, or 0 if it verified a predigested message. A
value of 0 indicates likely non-approved usage of the FIPS provider.
This flag is set when any signature verification initialisation
function is called. It is also set to 1 when any signing operation
is performed to signify compliance. See FIPS 140-3 IG 2.4.B for
further information.
"key-check" (OSSL_SIGNATURE_PARAM_FIPS_KEY_CHECK) <integer>
If required this parameter should be set early via an init function
(e.g. OSSL_FUNC_signature_sign_init() or
OSSL_FUNC_signature_verify_init()). The default value of 1 causes
an error during the init if the key is not FIPS approved (e.g. The
key has a security strength of less than 112 bits). Setting this to
0 will ignore the error and set the approved "indicator" to 0. This
option breaks FIPS compliance if it causes the approved "fips-
indicator" to return 0.
"digest-check" (OSSL_SIGNATURE_PARAM_FIPS_DIGEST_CHECK) <integer>
If required this parameter should be set before the signature digest
is set. The default value of 1 causes an error when the digest is
set if the digest is not FIPS approved (e.g. SHA1 is used for
signing). Setting this to 0 will ignore the error and set the
approved "fips-indicator" to 0. This option breaks FIPS compliance
if it causes the approved "fips-indicator" to return 0.
"sign-check" (OSSL_SIGNATURE_PARAM_FIPS_SIGN_CHECK) <integer>
If required this parameter should be set early via an init function.
The default value of 1 causes an error when a signing algorithm is
used. (This is triggered by deprecated signing algorithms). Setting
this to 0 will ignore the error and set the approved "fips-
indicator" to 0. This option breaks FIPS compliance if it causes
the approved "fips-indicator" to return 0.
"sign-x931-pad-check" (OSSL_SIGNATURE_PARAM_FIPS_SIGN_X931_PAD_CHECK)
<integer>
If required this parameter should be set before the padding mode is
set. The default value of 1 causes an error if the padding mode is
set to X9.31 padding for a RSA signing operation. Setting this to 0
will ignore the error and set the approved "fips-indicator" to 0.
This option breaks FIPS compliance if it causes the approved "fips-
indicator" to return 0.
OSSL_FUNC_signature_gettable_ctx_params() and
OSSL_FUNC_signature_settable_ctx_params() get a constant OSSL_PARAM(3)
array that describes the gettable and settable parameters, i.e.
parameters that can be used with OSSL_FUNC_signature_get_ctx_params()
and OSSL_FUNC_signature_set_ctx_params() respectively.
MD parameters
See OSSL_PARAM(3) for further details on the parameters structure used
by the OSSL_FUNC_signature_get_md_ctx_params() and
OSSL_FUNC_signature_set_md_ctx_params() functions.
OSSL_FUNC_signature_get_md_ctx_params() gets digest parameters
associated with the given provider side digest signature context ctx and
stores them in params. Passing NULL for params should return true.
OSSL_FUNC_signature_set_ms_ctx_params() sets the digest parameters
associated with the given provider side digest signature context ctx to
params. Any parameter settings are additional to any that were
previously set. Passing NULL for params should return true.
Parameters currently recognised by built-in signature algorithms are the
same as those for built-in digest algorithms. See "Digest Parameters" in
provider-digest(7) for further information.
OSSL_FUNC_signature_gettable_md_ctx_params() and
OSSL_FUNC_signature_settable_md_ctx_params() get a constant
OSSL_PARAM(3) array that describes the gettable and settable digest
parameters, i.e. parameters that can be used with
OSSL_FUNC_signature_get_md_ctx_params() and
OSSL_FUNC_signature_set_md_ctx_params() respectively.
RETURN VALUES
OSSL_FUNC_signature_newctx() and OSSL_FUNC_signature_dupctx() should
return the newly created provider side signature context, or NULL on
failure.
OSSL_FUNC_signature_gettable_ctx_params(),
OSSL_FUNC_signature_settable_ctx_params(),
OSSL_FUNC_signature_gettable_md_ctx_params() and
OSSL_FUNC_signature_settable_md_ctx_params(), return the gettable or
settable parameters in a constant OSSL_PARAM(3) array.
OSSL_FUNC_signature_query_key_types() should return a NULL-terminated
array of strings.
All verification functions should return 1 for success, 0 for a non-
matching signature, and a negative value for operation failure.
All other functions should return 1 for success and 0 or a negative
value for failure.
SEE ALSO
provider(7), "Provider Functions" in provider-base(7), OSSL_PARAM(3),
OSSL_DISPATCH(3), OSSL_ALGORITHM(3), EVP_PKEY_sign(3),
EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3), EVP_SIGNATURE_is_a(3),
ASN1_item_sign_ctx(3)
HISTORY
The provider SIGNATURE interface was introduced in OpenSSL 3.0.
The OSSL_FUNC_signature_sign_message_init(),
OSSL_FUNC_signature_sign_message_update(),
OSSL_FUNC_signature_sign_message_final(),
OSSL_FUNC_signature_verify_message_init(),
OSSL_FUNC_signature_verify_message_update() and
OSSL_FUNC_signature_verify_message_final() functions were added in
OpenSSL 3.4.
The Signature Parameters "fips-indicator", "key-check" and "digest-
check" were added in OpenSSL 3.4.
Deterministic digital signature generation for ECDSA was added to the
FIPS provider in OpenSSL 3.6.
COPYRIGHT
Copyright 2019-2025 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.5.5 2026-01-27 PROVIDER-SIGNATURE(7SSL)
Generated by dwww version 1.16 on Fri Mar 20 17:40:38 CET 2026.